He is accused of using illegal tactics to win the mayoral election in Tower Hamlets, East London, in May.

On Tuesday it emerged four voters had won their bid to have a damaging dossier of evidence heard at a full trial. Mr Rahman has strenuously denied allegations of electoral fraud.

Mr Rahman has risked causing further anger with his decision to fly the flag of Palestine over the town hall.

He tweeted a photograph of the flag, with the message: "Palestinian flag flying at Town Hall in solidarity with #Gaza and in support of a ceasefire & peace."

The move risks angering the Jewish community in the east London borough and fuelling divisions in a borough increasingly used to making headlines for the wrong reasons.

A recent review found the council's handling of the local and European election count was 'inadequate'.

Tory party chairman Grant Shapps told MailOnline: "This is an administration that cannot even organise their own election count, let alone intervene on foreign affairs in the Middle East.

"What we need is an immediate ceasefire and continued humanitarian aid, rather than empty, flag-waving gesture politics."

It is not thought that there are any rules stopping the flying of the flag over a public building.

Jonathan Arkush, vice president of the Board of Deputies of British Jews, said: "Mayor Rahman should remember that he is flying a flag from a British town hall in support of an organisation that is regarded across Europe and the world as terrorist.

"It is totally inappropriate. It is also destructive of relations between the communities that make up our capital city."

In a statement Mr Rahman said: "We are flying the Palestinian flag over the town hall as a humanitarian gesture of our solidarity with the people of Gaza.

"In addition to the current military onslaught, the blockade of Gaza is causing a humanitarian catastrophe. Over 1,000 people have been killed, most of them women and children. An urgent aid corridor needs to be opened to allow those injured to receive treatment and medical care.

"We mourn the loss of life in this tragic conflict. We call on our Prime Minister to help create a lasting peace that breaks the cycle of violence between Israelis and Palestinians and prevents any further loss of innocent lives."

An estimated 1,200 Palestinians and 55 Israelis have been killed in the conflict. Israel launched its offensive in Gaza after a surge in rocket fire from the territory.

Hamas, which controls Gaza, has said it will not stop fighting until a blockade on the area, maintained by both Israel and Egypt, is lifted.

Already this month there have been angry rows about Preston Town Council and Bradford Council flying the Palestinian flag.

David Israel of the Leeds Jewish community said the Preston council was wrong to take sides in the conflict. "Innocent Israeli civilians have suffered through war and conflict," he told the BBC.

"If you're going to put up one flag you need to put up the other flag to show support for innocent civilians on both sides on the conflict."